ERBB2 and neoplasm: Among IHC 2+ tumours, the pCR rate following chemotherapy alone was as follows: 12.5% (2/16) in the HER2 amplified group (Groups 1, 2 and 3); 12.5% (1/8) in Group 1; 16.7% (1/6) in Group 2; 0% (0/2) in Group 3; 12.6% (19/151) in the HER2 non-amplified group (Groups 4 and 5).